Chair back



FIG. 1 is a perspective view of a chairback showing my new design;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a rear elevational view thereof;

FIG. 4 is a side elevational view thereof;

FIG. 5 is a top plan view thereof; and

FIG. 6 is a bottom plan view thereof.

The side of the chair back not shown is a mirror image of the side shown in FIG. 4.

The broken lines in the FIG. 1 description are for illustrative purposes only. 

The ornamental design for a chair back, as shown and described. 